It is known that due to the transparency, cured products obtained by curing epoxy resin compositions containing acid anhydride-based curing agents are suitably used as sealing materials for optical semiconductor elements such as light emission diodes and photodiodes.
As transparent cured products, typically cured products cured by hydrosilylation of siloxane containing an alkenyl group and siloxane containing an Si—H group (for example, see PTL 1) or the like are known.
However, as the performance of optical semiconductors has recently progressed, higher performance has been required for the resins for sealing the optical semiconductors, and cured products having excellent hardness and excellent resistance to yellowing by heat in which no discoloring or the like occurs even if a treatment at high temperature is performed.